The past several decades have seen remarkable advances in audio and video reproduction equipment, particularly equipment that allows a variety of audio tracks to be carried or transported with a user from one location to another. Such equipment includes, e.g., equipment for digitally recording, editing, mixing, producing, storing and reproducing audio tracks. Digital files are advantageous for several reasons, including the fact that running error correction algorithms on the files can guarantee that the audio track data in the files is properly stored, which means that the audio can be faithfully reproduced even where an underlying recording medium induces errors or where errors are induced in the copy process. Another advantage of digital files is that reproduction equipment can precisely control the speed at which the audio track is played, thereby effectively guaranteeing consistent playback.
In recent years, new algorithms for storing audio tracks have emerged. One of the more popular of these new audio track storage algorithms is the Motion Picture Entertainment Group level 3 algorithm, commonly referred to as the “MP3” algorithm. The MP3 algorithm uses a variety of techniques, including allowing users to vary the audio track sampling rate as the audio track is recorded, varying the number of bits used to represent a given frequency range, and the like, to generate digital audio track files that are significantly smaller than those used on CD's. This means that users can carry more audio data files on a given medium than they could in the past. For example, a typical seventy-two minute audio CD holds approximately 650 MB of data. Depending on the compression methods chosen, a 650 MB CD-ROM has sufficient capacity for several hours of compressed music.
As digital storage capacity continues to increase and compression algorithms continue to advance, users are able to carry more and more of the music they like with them. This has resulted in the incorporation of audio track reproduction capabilities in an ever-increasing array of audio-capable devices, including, but not limited to, digital cameras, portable digital assistants (“PDA's”), wireless telephones, and the like. Several other devices, generally referred to as portable media players (“PMP's”), have been introduced into the market that are predominately used for reproduction of compressed audio tracks. One of the most popular PMP's is the iPod, sold by Apple Computer, Inc. of Cupertino, Calif. The iPod has become popular because it has a relatively small form factor but can store many gigabytes of audio files and other information on a hard disk drive stored within the PMP. Other PMPs additionally store video information for playback on a small display integrated into the device.
Most of the currently available audio devices are designed to be highly portable and to allow an individual to carry a relatively large number of audio tracks. However, because design of these devices has centered on portability, manufacturers tend to limit them so as to present the reproduced audio to a user only through monaural or stereo headphones that are plugged into the audio device. This means that, at best, these audio devices can only be used to reproduce audio tracks for a limited number of users, such as where one or more splitters are used to allow multiple users to plug headphones into the device. However, because the audio devices are typically battery powered, they are not capable of generating enough energy to power several pairs of headphones. Furthermore, increasing the number of users connected to a single device beyond one or two limits the device's portability.
One method alternatively employed by some in the prior art is to allow users to attach speakers to a portable media player. This allows multiple users to experience audio tracks at the same time. Because the power output of audio devices is typically relatively low, it is frequently advantageous for the speakers to include an amplifier which is powered by an external power source. Some in the prior art have created relatively small, battery powered or alternating current (AC) powered speakers for use with portable audio reproduction equipment. These speakers tend to take a lot of physical abuse during transportation, and frequently the cables and adaptors used to connect the speakers to the audio device are not capable of withstanding such abuse.
One solution offered on the market is the original inMotion™, available from Altec Lansing Technologies, Inc., of Milford, Pa., and described in U.S. patent application Ser. No. 10/836,113 filed Apr. 30, 2004. The inMotion™ was a groundbreaking product which, for the first time, provided powered speakers integrated with a docking station for a portable media player in a relatively lightweight and compact portable package that folded to protect the speaker drivers during transport. While the inMotion™ offered great advantages in terms of robustness, weight, portability, size, and ease-of-use, room for improvement in each of these qualities remains.